The stumbling block

The stumbling block of Western lore 
Is faith in old arithmetics—
That two and two are always four 
And three and three make ever six 
Whereas 'neath less exacting skies, 
These numbers total otherwise, 
Equality of A to B
Is interesting—Greenwich way;
But does not for a moment pred-
-icate the like 'twixt B and A. 
For East of Suez, be it said
B is the sum of XYZ.
It may be heat or damp or dew
That warps the numbers, one to ten, so 
And twists the alphabet askew 
Disproving Euclid and Colenso;
Or else there must be people who
Don't think as other people do.